Mechanical Unfolding of an Autotransporter Passenger Protein Reveals the Secretion Starting Point and Processive Transport Intermediates
Mechanical Unfolding of an Autotransporter Passenger Protein Reveals the Secretion Starting Point and Processive Transport Intermediates
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DOI：
10.1021/acsnano.5b07072
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发表时间：
2016-06-01
期刊：
影响因子：
17.1
通讯作者：
Wuite, Gijs J. L.
中科院分区：
文献类型：
--
作者：
Baclayon, Marian;van Ulsen, Peter;Wuite, Gijs J. L.
分泌的自转运蛋白乘客蛋白的骨架通常获得稳定的β-螺旋结构。乘客分泌穿过外膜被认为是由细胞表面的这种结构的顺序折叠驱动的。这一机制需要一个相对稳定的中间体作为起点。在这里，我们研究了机制分泌截断版本的自转运血红蛋白酶（Hbp）的大肠杆菌使用原子力显微镜。所获得的数据揭示了在C末端的非常稳定的β-螺旋结构。此外，还发现了其他几种不同的亚稳中间体，它们在解折叠过程中通过多途径连接。计算分析表明，这些中间体与Hbp结构中的β-螺旋梯级相关，这些梯级被堆叠的芳族残基夹持。我们的研究结果表明，这是一个分泌机制，是由一个稳定的C-末端结构和驱动的几个折叠中间体，建立了β-螺旋骨架向前。
The backbone of secreted autotransporter passenger proteins generally attains a stable beta-helical structure. The secretion of passengers across the outer membrane was proposed to be driven by sequential folding of this structure at the cell surface. This mechanism would require a relatively stable intermediate as starting point. Here, we investigated the mechanics of secreted truncated versions of the autotransporter hemoglobin protease (Hbp) of Escherichia coli using atomic force microscopy. The data obtained reveal a beta-helical structure at the C terminus that is very stable. In addition, several other distinct metastable intermediates are found which are connected during unfolding by multiroute pathways. Computational analysis indicates that these intermediates correlate to the beta-helical rungs in the Hbp structure which are clamped by stacked aromatic residues. Our results suggest a secretion mechanism that is initiated by a stable C-terminal structure and driven forward by several folding intermediates that build up the beta-helical backbone.